In recent years, in accordance with improvement in performance of color image reading devices (scanners) and color printers, there is an increasing risk of counterfeiting a particular original such as a bank note or a negotiable instrument by reading the original from a color scanner and outputting the read image data to a color printer.
To prevent the counterfeiting, color copying machines, having a construction as a combination of color scanner and color printer, often incorporate a counterfeit prevention device which discriminates whether or not an original to be processed is such particular original and performs duplication prohibition processing.
However, the counterfeit prevention device used in the above color copying machines operate only in duplication processing. Accordingly, in a system where a scanner is connected to a printer via a host computer, there is a possibility that a counterfeit can be obtained by once reading a duplication-prohibited original by the scanner or the like then storing the read image data, and outputting the stored image data by the color printer. Further, generally, the above conventional counterfeit prevention device is expensive, therefore it is difficult to incorporate the device into small and low-price color copying machines and printers.
On the other hand, a so-called electronic watermark technique of embedding copyright information or the like in digital contents of image or music, is being practically used, and the application of electronic watermark technique to the above-described counterfeit preventing device is proposed. For example, counterfeiting can be prevented by embedding information processed by the electronic watermark technique in a duplication-prohibited printed matter (particular original), and detecting the electronic watermark information upon duplication or printing of the printed matter.
However, in a case where counterfeit judgment processing based on the above-described electronic watermark is executed in a printer driver in a host computer, heavy load is posed on the CPU. Accordingly, the printing speed in the system or apparatus is seriously reduced by execution of the counterfeit judgment processing.